EFFECT OF INLET WINDOWS DEFLECTORS AND WINDBREAK WALLS HEIGHT ON THE PERFORMANCE OF NATURAL DRAFT COOLING TOWER UNDER CROSSWIND CONDITIONS

摘要

The environmental crosswind brings changes in the aerodynamic pattern inside and outside a cooling tower, destroys uniform flow, and may deteriorate the fill zone performance. The effect of inlet windows deflectors and windbreak walls on the performance of a natural draft cooling tower is studied by means of three-dimensional numerical modeling. An assumption of heat and mass transfer equivalence is adopted. The numerical model is tested and verified by experimental data. Nonlinear behavior of the functional dependence of performance on the crosswind velocity is demonstrated by the minimal (critical) wind velocity U-cr similar to 6.5 m/s. Utilization of the inlet window deflectors and windbreak walls do not change the value of the critical wind velocity, but may improve the performance of a natural draft cooling tower under moderate and strong wind conditions. Utilization of deflectors in the inlet windows increases the thermal efficiency of a cooling tower up to 8.6% at U > 2 m/s and has no effect at wind velocities close to Ucr. Utilization of windbreak walls of optimum height may increase the cooling tower efficiency up to 20-30%. It is demonstrated that the parameters of the vertical wind distribution influence the value of the critical wind velocity. The results of the work may be useful for optimal design of natural draft and "hybrid" cooling towers.